Iterating over URIs in json_file db is slow

[thorbjoernl]

Iterating over the URIs in a json database is currently extremely slow. The following quick benchmark illustrates the problem when iterating over the included test dataset which consists of only 39 objects.

import aerovaldb
import time

with aerovaldb.open("json_files:./tests/test-db/json") as db:
    start_time = time.perf_counter()
    count = len(list(db.list_all()))
    end_time = time.perf_counter()

print(f"json_files: {count} items in {end_time-start_time:.3f} seconds")

with aerovaldb.open("sqlitedb:./tests/test-db/sqlite/test.sqlite") as db:
    start_time = time.perf_counter()
    count = len(list(db.list_all()))
    end_time = time.perf_counter()

print(f"sqlite:     {count} items in {end_time-start_time:.3f} seconds")

# Output
# json_files: 39 items in 0.197 seconds
# sqlite:     39 items in 0.001 seconds